Name That Truck Part - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gringoloco · 01-05-2013, 06:59 PM

At risk of appearing a buffoon, can someone please enlighten me to this component's name/description/purpose? All it was good for was a fat vacuum leak before I capped it off.

Never had a truck this original before, so I'm kinda stumped. Chasing vacuum leaks during a tune up and found this mystery part sucking wind. '72 Blazer, 4wd, 350/350, A/C. This is bolted to the intake manifold, on the passenger side, just behind the choke:

**VetteVet** · 01-05-2013, 07:51 PM

From what I have read about the system I believe that might be the TCS vacuum switch.
It controls vacuum to the distributor to prevent vacuum advance until engine warm up.

TCS stands for transmission controlled spark. I think the green wire goes to the temp sender and the red wire goes to key on power.

JimKshortstep4x4 · 01-05-2013, 08:08 PM

In addition to the engine temperature as part of the control on the vacuum switch, the transmission has to be in high gear in order for the vacuum switch to allow the vacuum advance to operate.

There should be a switch on the transmission that is wired into the emission control system, (TCS).

Jim

gringoloco · 01-05-2013, 08:07 PM

Thanks! That makes sense. The tee before it is branched to the dizzy, so it is currently bypassed. Wonder where that teed line was supposed to go? The tee is an integral part of the assembly, not something someone put in there.
Posted via Mobile Device

gringoloco · 01-05-2013, 08:47 PM

Learn something new every day... Was this a '72 only thing? I thought non-California trucks were safe from this mess

Posted via Mobile Device

da-burb · 01-05-2013, 09:05 PM

I have seen it in that location on 1970's. My 71 suburban has it mounted to the front of the carb (same place as the 72's I have seen it on).

GASoline71 · 01-05-2013, 09:07 PM

My 1972 GMC had the TCS system on it when I got it. My truck has been in WA state for its entire life. I disabled it, and removed it.

Gary

custom1970 · 01-05-2013, 09:26 PM

http://67-72chevytrucks.com/vboard/s...d.php?t=464103

Try the above thread if you want some more info. Hope the link works, doing this from my I pad and its a little harder to paste things.
But, yes it's part of the TCS system.
Posted via Mobile Device

gringoloco · 01-05-2013, 10:27 PM

Thanks everyone. I've done a little research on the system and it seems capping the solenoid was the right thing to do

2500HD · 01-05-2013, 11:44 PM

It looks like I have one also. i have been wondering what it is. This is a 70 BBC 400 with California emmisions. I would like to delete....... what am i going to hurt and how would i go about it?

01-05-2013, 06:59 PM	#1
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,920	Name That Truck Part At risk of appearing a buffoon, can someone please enlighten me to this component's name/description/purpose? All it was good for was a fat vacuum leak before I capped it off. Never had a truck this original before, so I'm kinda stumped. Chasing vacuum leaks during a tune up and found this mystery part sucking wind. '72 Blazer, 4wd, 350/350, A/C. This is bolted to the intake manifold, on the passenger side, just behind the choke: Attached Images __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy

01-05-2013, 07:51 PM	#2
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,709	Re: Name That Truck Part From what I have read about the system I believe that might be the TCS vacuum switch. It controls vacuum to the distributor to prevent vacuum advance until engine warm up. TCS stands for transmission controlled spark. I think the green wire goes to the temp sender and the red wire goes to key on power. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

01-05-2013, 08:08 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Name That Truck Part In addition to the engine temperature as part of the control on the vacuum switch, the transmission has to be in high gear in order for the vacuum switch to allow the vacuum advance to operate. There should be a switch on the transmission that is wired into the emission control system, (TCS). Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

01-05-2013, 08:07 PM	#4
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,920	Re: Name That Truck Part Thanks! That makes sense. The tee before it is branched to the dizzy, so it is currently bypassed. Wonder where that teed line was supposed to go? The tee is an integral part of the assembly, not something someone put in there. Posted via Mobile Device __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy Last edited by gringoloco; 01-05-2013 at 08:13 PM.

01-05-2013, 08:47 PM	#5
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,920	Re: Name That Truck Part Learn something new every day... Was this a '72 only thing? I thought non-California trucks were safe from this mess Posted via Mobile Device __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy

01-05-2013, 09:05 PM	#6
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	Re: Name That Truck Part I have seen it in that location on 1970's. My 71 suburban has it mounted to the front of the carb (same place as the 72's I have seen it on). __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

01-05-2013, 09:26 PM	#8
custom1970 Member Join Date: Jan 2011 Location: Stuart, Florida Posts: 459	Re: Name That Truck Part http://67-72chevytrucks.com/vboard/s...d.php?t=464103 Try the above thread if you want some more info. Hope the link works, doing this from my I pad and its a little harder to paste things. But, yes it's part of the TCS system. Posted via Mobile Device __________________ 1970 CST LB Fleetside, 402 BB, PS, PB,AC 1968 Firebird 400 conv. 1965 Chris Craft 17' wood ski boat (SN #0001)

01-05-2013, 10:27 PM	#9
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,920	Re: Name That Truck Part Thanks everyone. I've done a little research on the system and it seems capping the solenoid was the right thing to do __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy

01-05-2013, 11:44 PM	#10
2500HD Registered User Join Date: Aug 2005 Location: DFW Posts: 268	Re: Name That Truck Part It looks like I have one also. i have been wondering what it is. This is a 70 BBC 400 with California emmisions. I would like to delete....... what am i going to hurt and how would i go about it? Attached Images __________________ 1970 Custom Original 400/400 Now ZZ454/4L80E/Edelbrock Pro-Flo 4/3:73 Eaton Posi PS PB and cold factory air Early Classic 4.5/6 Front 20X8.5 Riddler 4.75 inch bs Pirelli 255/40/20 Rear 20X10 Riddler 5.5 inch bs Toyo 295/40/40 Rear end is original wide 6 lug converted to 5 lug

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